Vitamin B9 (Folate)
vitamin
ApprovedGeneral information about nutrients. No diagnosis, no medical advice. If you take medication, are pregnant or have a medical condition, talk to your doctor before taking supplements.
Overview
Water-soluble B vitamin. Folate has a role in the process of cell division. Folate contributes to maternal tissue growth during pregnancy.
Interactions
Vitamin C protects reduced folate from oxidative degradation in the blood and tissues, maintaining its bioavailability. Low vitamin C accelerates folate depletion.
Without B12, folate becomes trapped as methylfolate (the 'methyl-folate trap'), rendering it metabolically inactive.
Research status
Folate is involved in DNA methylation.
Top 5 food sources
Expert opinions
NIH
The NIH UL of 1,000 mcg applies exclusively to synthetic folic acid because it can accumulate as unmetabolized folic acid (UMFA) in blood when it exceeds DHFR-reductase capacity, and may mask B12-deficiency-induced megaloblastic anemia while neurological damage progresses. There is no UL for natural food folate or supplemental L-methylfolate (5-MTHF), which bypass the DHFR bottleneck. RDA is 400 mcg DFE for adults and 600 mcg DFE during pregnancy. The US fortifies grain products with folic acid, while most European countries rely on voluntary enrichment and supplementation for women of childbearing age.
Recommended dose: 400 mcg DFE
Source: NIH
Dr. Strunz
Strunz supplements folate only as L-methylfolate (5-MTHF) at 0.8 to 2 mg, never as folic acid, because roughly 40% of Europeans carry MTHFR C677T or A1298C polymorphisms that reduce conversion of folic acid to the active form by 30 to 70%. He aims for homocysteine below 7 µmol/L and combines 5-MTHF with methylcobalamin (B12) and P-5-P (B6). His lab targets are serum folate >10 ng/ml and erythrocyte folate >400 ng/ml. He pairs folate dosing with B12 testing to avoid masking pernicious anemia.
Recommended dose: 0.8–2 mg (as 5-MTHF)
Source: Dr. Strunz
Expert profiles summarise publicly available statements. The named people do not cooperate with Stackwell and have not authorised these summaries. Not medical advice.
Methylfolate form preferred over folic acid. UL applies to synthetic forms only.